A large part of the apple crop is put into cold storage for a predetermined interval before the apples are brought to market. It has been found that while the apples are in cold storage an undesirable condition develops that is known as bitter pit and is characterized by small brown spots or streaks appearing on the flesh of the apples. It is known that a high calcium level in the fruit, either natural or infiltrated, will minimize bitter pit. Accordingly, various methods have been used to raise the calcium level in apples. In one method, the orchard is sprayed with calcium chloride solution and this method results in a calcium level that is a little higher but still below the desired level. In another method, the apples are dipped in a calcium chloride solution immediately after harvest and are then put into cold storage. Very little infiltration takes place during the dipping but, during cold storage, unrinsed calcium chloride slowly diffuses through the skin and enters the flesh of the apples. This diffusion method, while necessarily slow, has provided some benefit and it is being actively used commercially at present. Since it is desirable to infiltrate the calcium as quickly as possible to avoid bitter pit formation, vacuum infiltration has been attempted. This procedure involves the immersing of the fruit in a 4% calcium chloride solution, pulling a vacuum to remove some of the fruit gases, and releasing the vacuum with the fruit immersed. This method does infiltrate the desired amount of calcium into apples that have closed calyxes. However, some varieties of apples have a needle-like opening extending from the calyx or blossom end of the apple to the core cavity. When this method is used and the vacuum is released, an excessive amount of solution is forced into the core cavity of the apple resulting in core damage and imparting a bitter calcium chloride taste to the apple. To overcome this problem it has been proposed to vacuumize the apples, spray the solution on the apples instead of immersing them in the solution, and then break the vacuum. It is claimed that this spray-vacuumizing procedure does result in a sufficient amount of calcium being infiltrated into both open and closed core apples.
An object of the present invention is to provide an improved method of simultaneously infiltrating controlled amounts of calcium chloride in both open and closed core apples.